Former Ku Klux Klan Imperial Wizard Samuel Bowers died yesterday in a US state penitentiary in the Mississippi Delta.
The 82-year-old was serving a life sentence for the 1966 bombing death of civil rights leader Vernon Dahmer.
Bowers was convicted in August of 1998 of ordering the assassination.
Dahmer was a civil rights activist who fought for black rights during Mississippi's turbulent struggle for racial equality.
State Department of Corrections spokeswoman Tara Booth said Bowers died at approximately 11.30am (local time) of cardio pulmonary arrest in the Mississippi State Penitentiary Hospital in Parchman.
Dahmer's widow, Ellie Dahmer, said the death brought little closure to a wound she had nursed for decades.